Adult Life Cycle Research Articles

Regeneration, Stem Cells, and Aging in the Tunicate Ciona: Insights from the Oral Siphon.

Regeneration studies in the tunicate Ciona intestinalis have recently been focused on the potential of adult stem cells to replace injured tissues and organs during the adult life cycle using the oral siphon (OS) as a model. The OS has oral siphon pigment organs (OPOs) along its rim and an underlying network of muscle fibers in its tube. Different regeneration processes are triggered by OS amputation at the tip, along the tube, or at the base. One process involves the replacement of OPOs without new cell division by direct differentiation of locally deployed stem cells or stem cells that migrate from the branchial sac. Another process involves blastema formation by the migration of progenitor cells produced from branchial sac stem cells. The capacity for complete and accurate OS regeneration declines continuously during the adult life cycle. Finally, after an age threshold is reached, OS regeneration ceases in old animals. The loss of regeneration capacity in old animals involves the depletion of stem cells in the branchial sac, the inability of branchial sac progenitor cells to migrate to the sites of regeneration, and defective oral pigment organ replacement. The significance of the OS model for studying regeneration, stem cells, and aging will be enhanced by the application of molecular methods.

Constructing Full Adult Life-cycles from Short Panels

In this paper we discuss two alternative approaches to constructing complete adult life-cycles using data from an 18-year panel. The first of these is a splicing approach - closely related to imputation - that involves stitching together individuals observed at different ages. The second is a microsimulation approach that uses panel data to estimate transition probabilities between different states at adjacent ages and then simulates a large number of individuals with different initial values. Our aim throughout is to construct life-cycle profiles of employment, earnings and family circumstances that are representative of UK individuals born between 1945 and 1954. On balance, we find the microsimulation approach is to be preferred because it allows us to correct for observable differences across cohorts, and it is more amenable to counterfactual modelling.

Resistance of collard greens to Ascia monuste orseis (Lepidoptera: Pieridae)

Ascia monuste orseis (Godart) (Lepidoptera: Pieridae) is a production limiting pest in collard greens, Brassica oleracea (L.) var. acephala, cultivation. Because of the overuse and harmful effects of synthetic insecticides on nontarget species, the use of insect-resistant cultivars can be a valuable strategy in pest control. In this study, newly hatched A. monuste orseis larvae were confined to the leaves of 29 collard greens cultivars under a controlled environment to investigate plant resistance. We evaluated the incubation period, duration of instars, total duration of the immature and pupal phases, the egg to adult life cycle duration, mortality per instar, total weight of fifth instar larvae and pupae (age = 24 h) and larval and pupal survival and eclosion. Antibiosis and/or antixenosis were observed in selected cultivars. The results show that Gigante I-915 (E) exhibited high larval mortality and that the Pires 1 de Campinas cultivar (P) prevented all pupae from proceeding to the adult stage. The Introducoes do municipio de Arthur Nogueira Z (Y), Cabocla (AA), Japonesa (R) and Manteiga de Mococa (M) cultivars prolonged the larval stage. Japonesa (R) and Introducoes do municipio de Arthur Nogueira Z (Y) increased the egg to adult developmental period, and the Japonesa (R) cultivar also prolonged the pupal stage. The Verde-escura (O), Crespa de Capao Bonito (I), Couve de folhas Manteiga 900 Legitima Pe Alto (AB), Gigante I-915 (E) and Manteiga Ribeirao Pires I-2446 (H) cultivars reduced the larval weight of A. monuste orseis.

Gene-environment interplay in Drosophila melanogaster: Chronic nutritional deprivation in larval life affects adult fecal output

Life history consequences of stress in early life are varied and known to have lasting impacts on the fitness of an organism. Gene-environment interactions play a large role in how phenotypic differences are mediated by stressful conditions during development. Here we use natural allelic ‘rover/sitter’ variants of the foraging (for) gene and chronic early life nutrient deprivation to investigate gene-environment interactions on excretion phenotypes. Excretion assay analysis and a fully factorial nutritional regimen encompassing the larval and adult life cycle of Drosophila melanogaster were used to assess the effects of larval and adult nutritional stress on adult excretion phenotypes. Natural allelic variants of for exhibited differences in the number of fecal spots when they were nutritionally deprived as larvae and well fed as adults. for mediates the excretion response to chronic early-life nutritional stress in mated female, virgin female, and male rovers and sitters. Transgenic manipulations of for in a sitter genetic background under larval but not adult food deprivation increases the number of fecal spots. Our study shows that food deprivation early in life affects adult excretion phenotypes and these excretion differences are mediated by for.

Psyllid Host-Plants (Hemiptera: Psylloidea): Resolving a Semantic Problem

Evolutionary and biological patterns can be obscured by inadequate or ill-defined terminology. An example is the generally very specific relationship between the sap-feeding hemipteran group, psyllids, and their breeding plants, commonly called host-plants. The literature is clogged with references to so called ‘hosts’, which are often merely plants on which psyllids were found accidentally, and no immature development was detected. Recently the term host has also been applied by some authors to any plant on which immature or adults feed. Here we propose a terminology to clarify associated plant definitions, and we suggest restricting the use of the term host-plant to plants on which a psyllid species completes its immature to adult life cycle. For the other plant associations we suggest the terms overwintering or shelter plant (plants on which adult psyllids overwinter and on which they may feed), food plant (plants on which adult psyllids feed, but do not breed and do not spend an extended period of time) and casual plant (plants on which adult psyllids land but do not feed).

The balance of intergenerational family transfers: a life-cycle perspective.

The aim of this study is to determine the likelihood and net amount of parent-child transfers over the adult life cycle across European welfare regimes. The study introduces an economic life-cycle model of family transfers to describe the evolution of family exchanges across generations over time, which reveals a nonlinear relationship of age and net family transfers. Furthermore, it refines the method of estimating parent-child net transfers. Data come from the Survey of Health, Ageing, and Retirement in Europe, and include 36,095 parent-child dyads from 11 European countries representing social democratic, conservative, and traditional welfare-state regimes. The findings reveal net value of family intergenerational support follows a nonlinear pattern across the adult life cycle, with positive transfers from parents to adult children decreasing modestly until advanced old age when the decrease intensifies. Net family support benefits individuals and generations with larger relative need. The transition in the net family support pattern starts later and is less pronounced across social democratic welfare-regime countries while the opposite is true in traditional welfare-regime countries. These findings might be interpreted as being linked to differences in the public policies guaranteeing different levels of provision for dependent populations across different welfare regimes. They are consistent with a comparatively smaller role of family support in the intergenerational redistribution of resources in societies with larger public intergenerational support to dependent populations.

BIOLOGICAL STUDY OF TWO SPOTTED SPIDER MITE Tetranychus sp. (ACARI: TETRANYCHIDAE) ON THREE LEAF PHASES OF MUNG BEAN AND ADZUKI BEAN FOR MITE MASS REARING

Two-spotted spider mite (TSM) Tetranychus sp. is one of prey mites for phyotoseiid mite mass rearing. Based on previous research that TSM population developed well on Mung bean ( V igna radiata ) and Adzuki bean ( V . angularis ) as host plants, confirmed growth and development of TSM on both beans. Research was aimed to observe biology of TSM on three phases of Mung bean and Adzuki bean leaf such as at primary leaf unrolled completely (V1), at the 1 st trifoliate unrolled completely (V2), and at the 2 nd trifoliate unrolled completely (V3). Pre adult stadia, life cycle, male and female longevity, female fecundity of TSM, and trichome density were observed on petri dishes contained each leaf phase of beans. Result showed that three leaf phases of beans did not influence significantly in all biological variables, except fecundity. TSM fecundity was the highest on V3 phase of Mung bean (86.90). Trichome density on Mung bean leaf surface per mm² was lower than Adzuki bean. Trichome density of upper leaf surface of V3 phase of Mung bean (10.53) and Adzuki bean (3.07) were lower than V1 (13.20; 12.40) and V2 phase (6.20; 5.27). V3 phase of Mung bean was most suitable for TSM mass rearing. Key words: fecundity, leaf phase, mass rearing, trichome density, two-spotted spider mite

Does Choice Bring Loyalty? Electoral Participation and the Development of Party Identification

Party identification is known to influence almost all aspects of political life. How this attachment develops across the adult life cycle, however, remains unknown. I argue that people reinforce their partisan predispositions by voting for their preferred party. Voting entails a choice over a set of alternatives. This choice is likely to induce rationalization. In so doing, it provides signals of group identity, which in turn strengthens people's partisan ties. Testing this hypothesis is made difficult because it implies a reciprocal relationship between partisanship and vote choice. I address this problem by using vote eligibility as an instrument of vote in a sample of almost equally aged respondents. The results indicate that elections fortify prior partisan orientations. Moreover, they do so not by increasing political information. Rather, it is the act of voting for a party that, itself, bolsters partisan attachment. This act leaves a long‐lasting imprint on people's partisan outlooks.

Financial Literacy and Credit Card Behaviors: A Cross-Sectional Analysis by Age

In this study, we use a measure of financial literacy that includes both a test score of actual financial literacy and a self-rating of perceived financial literacy to investigate how financial literacy affects five credit card behaviors: (1) always paying a credit card balance in full; (2) carrying over a credit card balance and being charged interest; (3) making only a minimum payment on a credit card balance; (4) being charged a fee for a late payment; and (5) being charged a fee for exceeding a credit limit. Probit analysis was used to assess each behavior with a large nationally representative sample of U.S. adults (N = 28,146) divided into groups to reflect the five major decades in the adult life cycle (18–29; 30–39; 40–49; 50–59; and 60–69 and older). Perceived financial literacy was found to be a stronger predictor of less costly practices in credit card use than actual financial literacy for the five credit card behaviors and across each of the five age groups. The study also shows that the combination of the subjective assessment with the objective assessment of financial literacy provides a more comprehensive analysis of how financial literacy affects each credit card behavior. This combined approach to assessment produced the largest estimates of the effects of financial literacy on credit card behavior. The findings hold across the five credit card behaviors and the five age groups.

Apoptosis phenomenon in the schistosomulum and adult worm life cycle stages of Schistosoma japonicum

Apoptosis is an important aspect of a number of biological processes, from embryogenesis to the stress–injury response. It plays a central role in balancing cell proliferation and tissue remodeling activity in many organisms. In the present study, apoptosis in 14days post infection schistosomula was evaluated using TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assays and DAPI staining. Additionally, flow cytometry using the Annexin V-FITC/propidium iodide (PI) (Annexin V/PI) assay confirmed the percentage of early apoptotic, late apoptotic, and necrotic cells in 14 and 23days post infection worms. Conserved Domain Database (CDD) BLAST analysis and alignment analysis of known schistosome proteins demonstrated the feasibility of detecting the activity of caspase-3 and -7 using the caspase-3/7 Glo analysis assay. Analysis of caspase-3 and -7 activities in schistosome demonstrated that both caspases were active in each developmental stage of Schistosoma japonicum, but was highest in the 14days post infection schistosomula. Additionally, the caspase peptide inhibitor (Z-VAD-FMK) inhibited the caspase-3/7 activity at all developmental stages examined. Therefore, we hypothesized that two main signaling pathways are involved in apoptosis in S. japonicum, the caspase cascade and the mitochondrial-initiated pathway. We have constructed a model of these two pathways, including how they may interact and their biological outcomes. qRT-PCR analyses of the gene expression profiles of apoptosis-related genes supported our hypothesis of the relationship between the apoptotic pathway and parasite development. The data presented here demonstrates that apoptosis is an important biological process for the survival and development of the schistosome, and identifies potential novel therapeutic targets.

Family policy and couples’ labour supply: an empirical assessment

This paper empirically examines the effect on couples’ labour supply of a universal at-birth cash benefit and a government subsidy equal to 50% of child care expenditure for working parents. The method is first to simulate the effects on labour supply over the adult lifecycle using a calibrated dynamic utility maximisation model of a representative couple, using data drawn from waves of a longitudinal survey for Australia. Then using the same data, the effect of family benefits and the child care subsidy on couples’ hours worked is econometrically estimated. The 50% child care subsidy was found to increase the average couple’s labour supply by the equivalent of 0.75 to 1 h per week whilst children are of pre-school age, and less on average over the couple’s working lifetime. The cash benefit changes were found to have a negligible effect on labour supply.

The microRNA miR-34 modulates ageing and neurodegeneration in Drosophila

Human neurodegenerative diseases possess the temporal hallmark of afflicting the elderly population. Hence, aging is among the most significant factors to impinge on disease onset and progression1, yet little is known of molecular pathways that connect these processes. Central to understanding this connection is to unmask the nature of pathways that functionally integrate aging, chronic maintenance of the brain and modulation of neurodegenerative disease. microRNAs (miRNA) are emerging as critical players in gene regulation during development, yet their role in adult-onset, age-associated processes are only beginning to be revealed. Here we report that the conserved miRNA miR-34 regulates age-associated events and long-term brain integrity in Drosophila, presenting such a molecular link between aging and neurodegeneration. Fly miR-34 expression is adult-onset, brain-enriched and age-modulated. Whereas miR-34 loss triggers a gene profile of accelerated brain aging, late-onset brain degeneration and a catastrophic decline in survival, miR-34 upregulation extends median lifespan and mitigates neurodegeneration induced by human pathogenic polyglutamine (polyQ) disease protein. Some of the age-associated effects of miR-34 require adult-onset translational repression of Eip74EF, an essential ETS domain transcription factor involved in steroid hormone pathways. These studies indicate that miRNA-dependent pathways may impact adult-onset, age-associated events by silencing developmental genes that later have a deleterious influence on adult life cycle and disease, and highlight fly miR-34 as a key miRNA with a role in this process

Population Density and Spatial Distribution Pattern of Hypera postica (Coleoptera: Curculionidae) in Ardabil, Iran

The alfalfa weevil, Hypera postica (Gyllenhal), feeds almost exclusively on alfalfa, Medicago sativa L. in most region of the world where forage crop is grown. It has been investigated the population density and spatial distribution of alfalfa weevil on alfalfa in Ardabil during 2010. Using a 0.25 m2 quadrate sample unit a reliable sample size was 65, with maximum relative variation of 15%. The relative variation (RV) of the primary sampling data was 13.6. The highest population density of the alfalfa weevil was recorded on 17th April. To estimate the spatial distribution pattern of this pest, data were analyzed through index of dispersion, Lloyd’s mean crowding, Morisita’s index and two regression models (Taylor’s Power Law and Iwao’s Patchiness Regression). Taylor’s model showed an aggregated distribution pattern for all life stages. Iwao’s patchiness regression indicated that larvae, adult and total life cycle had aggregated spatial distribution (tc < tt), while pupae of alfalfa weevil exhibited a random pattern. The index of dispersion and Lloyd’s mean crowding methods indicated an aggregated distribution for this insect. Spatial distribution parameters of this species are used to outline a sampling program as well as to estimate population density of H. postica development stages. Optimum sample sizes for estimates of larval density, at three levels of precision, are presented.

Sexual maturation and aging of adult male mealybug (Hemiptera: Pseudococcidae)

The physiological age of adult males of seven mealybug species was measured in relation to the elongation of the male pair of the waxy caudal filaments. These filaments begin to emerge after eclosion and reached their maximum length from 29.4-46.6 h. The studied males were divided into three age groups, expressed as percentages of the total waxy caudal filaments length. Attraction to a sex pheromone source was significantly higher in the oldest male group (maximum filaments growth) compared with youngest one. Only the oldest male group copulated successfully; few of the younger males tested displayed 'courtship' behavior towards conspecific virgin females. The calculated duration of the sexually active phase of the adult male life cycle varied among species ranging from 34.4 to 46.6 h. There were marked variations in the strength of attraction to a pheromone source according to time of day. There was a continuous decrease in sexual activity from morning to evening. Our findings reveal clear maturation periods for adult males of the seven studied species. The long immature phase of the adult male mealybug is probably also related to several physiological processes that are needed to complete male maturation. The most noticeable change is the elongation of the waxy caudal filaments. However, mating may be performed at any time ambient conditions are suitable. Whereas male mealybug flight towards a pheromone source is restricted to a few hours, the male may continue mating activity throughout its sexually active period.

The Life-History and Bionomics of the Apple Rust Mite Calepitrimerus baileyi (Acari: Eriophyidae)

Ecological studies on the apple rust mite Calepitrimerus baileyi Keifer was conducted for one year in an abandoned Anna apple orchard in Egypt Population dynamic of the eriophyid apple prey was affected by climatic conditions, and vertical distribution, and about 11 generations were recorded whole year. Leaves at middle levels of apple cultivar were found preferable to the mite feeding than those at the top and bottom. C. haileyi successfully developed to adult stage when reared on leaf discs from soft lateral apple branches. At 16 and 37°C, the adults began to slow down activity and then died. It was able to develop at temperature between 23-35oC and 65% R.H. Adult life cycle and longevity decreased with increasing temperature. Fecundity was highest at 35°C and averaged 23 eggs per female. Life table parameters showed that the intrinsic rate of natural increase (rm) increased with temperature increase to a maximum of 0. I 58 at 35°C. Population of C. baileyi multiplied I 5.94 times in a generation time f 17.47 days at 35°C and recorded 8.79 times in a generation time of 25.8 days at 23°C under laboratory conditions.

Psychological and Social Factors that Promote Positive Adaptation to Stress and Adversity in the Adult Life Cycle

The phenomenon of resilience reflects positive adaptation despite contexts of risk, significant adversity, or trauma (Masten and Powell 2003; Luthar 2006). The purpose of this investigation was to propose a mediation model to explain the relation between stress and some psychological and social resources that enhance positive adaptation throughout the entire adult life cycle, and to explore the moderator role of age and country of origin. The indicator of positive adaptation was life satisfaction (LS). The sample comprised 171 Mexicans and 154 Spaniards (N = 325), aged between 18 and 87 years. Mediation was tested by means of various hierarchical regression analyses, which revealed that the positive adaptation process is enhanced by a group of psychological and social resources that mediate the effects of stress on LS. Self-esteem, optimism, internal control, coping aimed at acceptance, and coping aimed at seeking emotional support, as well as social contacts can mediate the negative effects of stress. Finally, it was found that age moderates the internal control but none of the remaining variables whereas the country does not moderate the relation of the variables.

Rapid and cost-effective assessment of connectivity among assemblages of Choerodon rubescens (Labridae), using laser ablation ICP-MS of sagittal otoliths

A rapid and cost-effective assessment was required to provide advice to management on the connectivity between juvenile and adult life cycle stages of Baldchin Groper Choerodon rubescens, a labrid endemic to the west coast of Australia, which has high social value, but relatively low commercial fishery importance. To minimise costs we used laser ablation ICP-MS to analyse levels of a small suite of elements (Ca, Mg, Mn, Cu, Zn, Sr, Rb, Ba and Pb) at the margin (adult phase) and core (juvenile phase) of the same otoliths of adult C. rubescens, collected at ten locations in five management zones. The elemental composition of both otolith margins and cores differed significantly among management zones and in some cases among locations within zones. Similarity of the pattern of among-zone elemental composition in otolith margins and cores indicated that, when cores are laid down, individuals have already recruited to the zones they will occupy as adults and there is no evidence of discrete juvenile nurseries. Thus, movement of juvenile or adult C. rubescens is likely to occur at relatively small spatial scales. Monitoring and management of adult stocks at the management zone level may be appropriate to sustain stocks broadly, but may not detect more localised depletion. Methods of elemental analyses are discussed and costs and benefits of this study vs an equivalent tagging study were compared.

Wasteful Killing in Urban Black Widows: Gluttony in Response to Food Abundance

Current work in behavioral ecology contrasts traditional hypotheses of context-specific adaptation with the suggestion that behaviors are often coupled such that animals exhibit context-general behavioral syndromes. Wasteful killing, the partial consumption and/or abandonment of prey, is a perplexing phenomenon because the costs of this behavior seem high (e.g. energetic loss, risk of injury). Wasteful killing may be the product of a context-specific, adaptive foraging strategy restricted spatially and/or temporally to conditions of prey abundance. Alternatively, wasteful killing may represent a context-general syndrome of high aggression that results in the capture of prey that are not consumed. We investigated the conditions in which a web-building spider the North American black widow (Latrodectus hesperus) participates in wasteful killing. We employed a powerful repeated-measures design that reduces error variance by controlling for individual differences. Across the adult life cycle of female spiders collected from urban habitats throughout Phoenix, AZ, we repeatedly measured each spider’s foraging voracity and wastefulness after varied periods of food restriction (2, 7, and 14 d). While food restriction decreased body condition, condition alone was a poor predictor of voracity and wasteful killing. Our results indicate that previous food restriction i) shortens latency to attack, ii) heightens the number of prey killed per trial, and iii) reduces wastefulness. Latency to attack and wasteful killing were neither repeatable within individuals nor correlated with each other and therefore appear unlikely to be components of a behavioral syndrome. We discuss other possible benefits for wasteful killing in the contexts of predation risk and mate attraction.

BIOLOGICAL ASPECTS OF PEAR BUD MITE Eriophyes pyri (PAGENSTECHER) (ACARI : ERIOPHIDAE) UNDER DIFFERENT TEMPERATURES IN EGYPT

The pear bud mite or pear leaf – gall mite Eriophyes pyri (Pagenstecher) successfully developed from egg to adult stage when reared on terminal buds of soft apple divided branches dipped in test tubes at different temperatures and 65% R.H., for the first time. The effect of temperature on the development, reproduction and population growth was investigated. At 14 and 34 °C the adults began to slow down and ceased all activity and died. It was able to develop at temperatures between 17 and 29°C with 65 % R.H. inside apple buds. At least of 34 % of the generation time was spent in the egg stage at 29°C. Adult life cycle and longevity decreased with increasing temperature. Fecundity was highest at 29°C with 20.66 eggs per female. Life table parameters showed that the intrinsic rate of natural increase (rm) increased with temperature to a maximum of 0.153 at 29°C. The population of E pyri inside buds multiplied 14.31 times in a generation time of 17.29 days at 29°C and lowered to 4.06 times in a generation time of 23.40 days at 17 °C under the same laboratory conditions.

The determinants of bicycle helmet use: Evidence from Germany

Previous research has shown that the risks of serious injury or death from bicycling can be mitigated by the decision to wear a helmet. Drawing on a nationwide household survey conducted in 2008 in Germany, this analysis investigates the determinants of voluntary helmet use through a combination of descriptive analyses and econometric methods, the latter relying on variants of the probit- and heteroskedastic probit model. Confirming results uncovered elsewhere in the literature, we find that household demographics, residential location, and riding patterns are significant correlates of helmet use. Contrasting with other studies, however, we also find that women are significantly less likely to use a helmet than men, a discrepancy that holds over most of the adult life-cycle. The paper concludes by highlighting the scope for designing strategic information campaigns to promote helmet use.